Which group of representative elements contains atoms with three valence electrons in their ground state?

• A. Group 13 (Boron group)
• B. Group 2 (Alkaline earth metals)
• C. Group 1 (Alkali metals)
• D. Group 15 (Nitrogen group)

Answer: (A)

Verified step by step guidance

1. Recall that the group number of representative elements (main-group elements) corresponds to the number of valence electrons in their atoms. For example, Group 1 elements have 1 valence electron, Group 2 have 2 valence electrons, and so on.
2. Identify the group that contains atoms with three valence electrons by matching the group number to the number of valence electrons. Since the question asks for atoms with three valence electrons, look for the group number 13 (or IIIA in older notation), which is known as the Boron group.
3. Understand that Group 13 elements have the electron configuration ending in \(\dots ns^2 np^1\), which totals three valence electrons (2 from the s orbital and 1 from the p orbital).
4. Verify that other groups listed do not have three valence electrons: Group 1 has 1 valence electron, Group 2 has 2 valence electrons, and Group 15 has 5 valence electrons.
5. Conclude that the group containing atoms with three valence electrons in their ground state is Group 13, the Boron group.